Recognize -Wl,-Bsymbolic

Without -Bsymbolic, a symbol/function in a *.so can be overridden
by a symbol/function in the main module.
That is the default search order, but not supported by tcc.

With -Bsymbolic, the linker tries to resolve a symbol/function in
the current module first.
The loader in tcc implements this search order.

We do not distinguish -Bsymbolic and -Bsymbolic-function

--
By by ... Detlef

tcc.c

@@ -386,6 +386,8 @@ static int parse_args(TCCState *s, int argc, char **argv)
                     if (strstart(optarg, "-Ttext,", &p)) {
                         s->text_addr = strtoul(p, NULL, 16);
                         s->has_text_addr = 1;
+                    } else if (strstart(optarg, "-Bsymbolic", &p)) {
+                        s->symbolic = TRUE;
                     } else if (strstart(optarg, "--section-alignment,", &p)) {
                         s->section_align = strtoul(p, NULL, 16);
                     } else if (strstart(optarg, "--image-base,", &p)) {

tcc.h

@@ -445,6 +445,9 @@ struct TCCState {
     /* if true, all symbols are exported */
     int rdynamic;
 
+    /* if true, resolve symbols in the current module first (-Wl,Bsymbolic) */
+    int symbolic;
+
     /* if true, only link in referenced objects from archive */
     int alacarte_link;
 

tccelf.c

@@ -1575,6 +1575,10 @@ static int elf_output_file(TCCState *s1, const char *filename)
                     put_dt(dynamic, DT_SONAME, put_elf_str(dynstr, s1->soname));
                 put_dt(dynamic, DT_TEXTREL, 0);
             }
+
+            if (s1->symbolic)
+                put_dt(dynamic, DT_SYMBOLIC, 0);
+
             /* add necessary space for other entries */
             saved_dynamic_data_offset = dynamic->data_offset;
             dynamic->data_offset += sizeof(ElfW(Dyn)) * EXTRA_RELITEMS;